A massive asteroid the size of a ten-story building whizzed past the Earth inside the Moon's orbit Wednesday with almost nobody knowing about it. In fact, if not for PAN-STARRS, the space rock, designated 2014 DX110, would have literally gone unnoticed. The telescope picked up the Apollo asteroid, the name given asteroids that pass across Earth's path, on the last day of February. Not much warning from an asteroid that measures larger (45 feet by 100 feet) than the Chelyabinsk meteor.
Yahoo News reported March 4 that 2014 DX110 would pass just inside the Moon's orbit.
The close fly-by is reminiscent of asteroid 2012 DA14, a half-football field-sized rock, that buzzed the Earth last year, the same day the Chelyabinsk meteor stole the show by exploding in the Russian sky. Still, that asteroid was much closer, just inside the orbits of many of the satellites circling above the Earth.
According to USA Today, scientists note that some 20 asteroids the size of and smaller than 2014 DX110 whip past the planet every year. Last year, 21 asteroids of that size and smaller did so.
Lindley Johnson of NASA's Planetary Science Division said, "In the last year, 21 small asteroids ranging in size from 1 to 30 meters have come closer to Earth than this," he said. "The close approach of 2014 DX110 is really a non-event in our eyes."
Yet there is potential for an event...
2014 DX110 passed to within 217,000 miles of Earth, just inside the lunar orbit. It was traveling at 33,000 mph as it crossed Earth's orbit.
It is just such close encounters with Apollo asteroids that opens the eyes of humanity to the risk involved in continuing to fly blindly through space while massive chunks of matter -- asteroids, comets, planetoids -- fly as blindly, paths dependent upon the push-and-pull of gravitational forces, collisions, attrition, and trajectories. Somewhere in all of the whirling about, two bodies flying through space can collide.
According to the Daily Mail, there are 240 known Apollo asteroids in existence, although there are possibly over 2000 of the space rocks that measure at least one-third of a mile across. An asteroid of that size impacting the Earth would cause untold devastation.
Slooh astronomer Bob Berman noted in a statement: "‘On a practical level, a previously-unknown, undiscovered asteroid seems to hit our planet and cause damage or injury once a century or so, as we witnessed on June 20, 1908 [Tunguska, Russia] and February 15, 2013 [Chelyabinsk, Russia].
"Every few centuries, an even more massive asteroid strikes us — fortunately usually impacting in an ocean or wasteland such an Antarctica.
"But the on-going threat, and the fact that biosphere-altering events remain a real if small annual possibility, suggests that discovering and tracking all near Earth objects, as well as setting up contingency plans for deflecting them on short notice should the need arise, would be a wise use of resources."
In fact, according to risk assessment, the chances of asteroid 2014 DX110 hitting Earth were at 1 out of 10 million.
In an interesting aside, one could view the passage of the asteroid on the website for the Slooh Space Camera, which was tracking the asteroid. Well, "could have" might be more accurate in that so many users went online to get a view that the site crashed.
But another asteroid, 2014 EC, was discovered on March 4 and passed by the Earth at just past midnight on March 6, according to Phil Plait at Slate's "Bad Astronomy." Only half the size the Chelyabinsk meteor, this small asteroid passed to within 35,000 miles of the planet. Given that it was just discovered, preparing for a strike would have been nearly impossible.
To put matters in perspective, the Chelyabinsk meteor was an asteroid that came from the direction of the sun. Its existence was unknown until it streaked across the Russian sky and exploded, its detonation causing millions of dollars in damage injuring thousands of people that were hurled to the ground or struck by shockwave-created debris.